You’ll be a tiny nation isolated in a big world, with no say at the top table.

You’ll suffer economically, losing trade by leaving a big club.

You’ll be swimming against a tide of integration, cutting yourselves off while others work together.

These arguments may sound doubly familiar – they’re used by opponents of Scottish independence, and by Brussels when it argues against eurosceptics. After yesterday’s intervention in the Scottish debate by Jose Manuel Barroso, they’re now used by Brussels about Scotland, too.

This is a problem all too few Conservatives are alive to. In our enthusiasm to keep one of history’s most productive unions, the UK, together, we run the risk of undermining the arguments we will need in 2017 to secure our independence from one of history’s most damaging unions, the EU.

That’s not to say the two unions are in any way equivalent. Scotland gets a good deal from its union with England, Wales and the United Kingdom – generous Barnett Formula payments, over-representation in Westminster and MPs who vote on English affairs while enjoying devolution for itself – while the UK gets a rotten deal from Brussels, as a net contributor to a union which constantly acts against our national interest.

But it would be incredibly short-sighted not to realise the fact that the pro-EU lobby is, right now, compiling a list of all the things British unionists say to Scots in order to throw them back in our faces when the chance to leave the EU comes around.

The 2017 in/out referendum will be a battle between hope and fear. Eurosceptics will have a strong case for Britain to make its own way in the world, looking outward to trade freely with the vast majority of humanity and regaining control of our country from an inward-looking, lagging euroblock. We will be up against pro-EU voices who will try to raise spectres of isolation, trade barriers and even the (absurd) prospect of war in Western Europe.

As I wrote last week, already we can see Brussels issuing threats of protectionism against the Swiss just because they dared to vote to regain control of their own borders.

It’s perfectly possible to believe that the UK is Better Together, and that our country would be Better Off Out of the EU. But if you want to secure the latter then you must be careful of how you go about securing the former.

After a torrid week for Alex Salmond, the temptation will be to go all out for the political destruction of Scottish separatism – going beyond the reasonable case for what Scotland would lose if it was to leave the “rUK” and raising spectre after spectre about the supposed impossibility of life for an independent nation in the 21st century. That approach might well put the Scottish referendum beyond all doubt – but it would also severely harm the victory we must win in 2017 if we want to regain control of our own country from the economically damaging, anti-democratic European Union.